20v is used as stock for ppl who are not into mods. and 16v is basic design . simpler to mod.
levin is right.mostly all 20v's in pak are NA's or lightly modified....
well the only difference is the head design with 5 valves per cylinder designed by Yamaha. yes the 16v are easier to work with then the 20v but then they can be modified to ppl requirements.
I wish i cud get my hands on it for free